Circular dichroism studies of sheep β-lipotropic hormone

St‐Pierre, Serge; Gilardeau, C.; Chrétien, Michel

doi:10.1139/o76-143

Cited by 17 publications

(10 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarly, /3-lipotropin is reported to contain about 12% a-helix in dilute salt solutions, which increases to 30% in 50% dioxane/water (20). The ability of nonpolar solvents to produce helical structures in /3-lipotropin has also been observed by Makarov et al (21).…”

mentioning

confidence: 54%

“…2. For these reasons the value of 29% a-helix previously reported for #,-lipotropin in 50% dioxane/water (20) should be considered only tentative. Nevertheless, it is apparent from our data that both polypeptides, in either methanol or NaDodSO4 solutions, contain an appreciable amount of helical conformation, perhaps as much as one-half of the molecules.…”

Section: Discussionmentioning

confidence: 97%

See 1 more Smart Citation

Conformation of beta-endorphin and beta-lipotropin: formation of helical structure in methanol and sodium dodecyl sulfate solutions.

Yang¹,

Bewley²,

Chen³

et al. 1977

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

ABSTRACTr Circular dichroic spectra of camel fl-endorphin and ovine f3-lipotropin in water show little, if any, secondary structure. Intrinsic viscosities and sedimentation coefficients of the two peptides also suggest that the molecules are not compact and globular. Methanol or sodium dodecyl sulfate promotes the formation of helical structure to an extent as much as one-half of either peptide molecule. The The presence of an endogenous ligand for the opiate receptor found in brain tissue has been demonstrated by Terenius, Snyder, Simon, and their coworkers (1-3), using a modification of a method suggested by Goldstein et al. (4). Two pentapeptides with opiate-like activity (Met-enkephalin, H-Tyr-GlyGly-Phe-Met-OH, and Leu-enkephalin, H-Tyr-Gly-Gly-PheLeu-OH) were isolated from pig brains by Hughes et al. (5). A polypeptide with potent opiate-like activity was isolated from camel pituitary glands by Li and Chung (6), and its amino acid sequence, identical to the COOH-terminal 31 amino acid residues of sheep /3-lipotropin (7-9), was determined (6). This peptide was designated /3-endorphin. The enkephalins (5) are related to the first five NH2-terminal residues of /3-endorphin (6). Both camel and human endorphins have been synthesized (10,11). Their sequences (6, 12) differ in only two positions (see Fig. 1). These two molecules are equipotent in both in vitro (12) and in vivo (11) bioassays for opiate-like activity.The conformations of the enkephalins, /3-endorphin, and /3-lipotropin have been investigated by several groups. Proton magnetic resonance studies have suggested that Met-enkephalin exists as a single (-turn in fully deuterated dimethyl sulfoxide (13-16), while circular dichroism (CD) studies indicate that the addition of salt to aqueous solutions of Met-enkephalin induces a "/3-like" structure (17). Little is known about the conformations of the (3-endorphins, although two preliminary reports have indicated that these molecules are low in helical content in water, but become more helical in trifluoroethanol (18,19).Similarly, /3-lipotropin is reported to contain about 12% a-helix in dilute salt solutions, which increases to 30% in 50% dioxane/water (20). The ability of nonpolar solvents to produce helical structures in /3-lipotropin has also been observed by We report here on the conformations of human /3-endorphin (/3h-endorphin) and camel /3-endorphin (/3c-endorphin) and sheep /3-lipotropin (/3,-lipotropin) in water, methanol, and sodium dodecyl sulfate (NaDodSO4) solutions as determined by CD and hydrodynamic studies. In addition, the limitations ofThe costs of publication of this article were defrayed in part by the payment of page charges from funds made available to support the research which is the subject of the article. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact. 3235predicting the secondary structure of these types of molecules from their primary structure, and of interpreting their CD spectra in terms of s...

show abstract

mentioning

confidence: 54%

Section: Discussionmentioning

confidence: 97%

Conformation of beta-endorphin and beta-lipotropin: formation of helical structure in methanol and sodium dodecyl sulfate solutions.

Yang¹,

Bewley²,

Chen³

et al. 1977

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…The same type of CD spectrum was obtained for sheep P-LPH in aqueous solution (pH 6.8), which was insensitive to temperature from 15 to 5OOC. 3 At pH 5.9,7.0, and 10.4, the CD spectra of porcine P-LPH in aqueous solution were the same. The presence of a large amount of ordered secondary structure in the pancreatic trypsin inhibitor (Kunitz)I3 and the resemblance of the CD spectrum of this protein in aqueous solution (pH 7.8)14 to P-LPH [ Fig.…”

Section: Methodsmentioning

confidence: 87%

Secondary structure of polypeptide hormones of the anterior lobe of the pituitary gland

Makarov¹,

Ng²,

Lobachov

et al. 1984

Biopolymers

View full text Add to dashboard Cite

SynopsisThe specific secondary structure of a number of polypeptide hormones of the pituitary gland anterior lobe and their fragments were studied by CD in the peptide bond absorption region and by ir spectroscopy. The state of objects was examined in solvents of different polarity over a wide temperature range as well as in the solid state at different relative humidities. The predominant conformational state of a number of hormones in aqueous solution is shown to represent a left-handed helix of the poly(L-proline) I1 type. The reversible melting process of the left-handed helical conformation when heated in an aqueous solution appears to be noncooperative. Lowering the temperature stabilizes the left-handed structure. The transition mode of the left-handed form to the a-, and the p-forms on changing the solvent conditions was also studied. Contributions of peptide chromophores and of the aromatic amino acid side-group chromophores with CD bands in the region under study were determined by analysis of CD spectra. The data obtained allow correlating the conformation of separate fragments in the hormone chain with functional activity. INTRODUCTIONTo polypeptide hormones of the anterior lobe of the pituitary gland are related a number of small peptides (from 13 to 93 amino acid residues) exhibiting partially overlapping activity. Of these the conformations of adrenocorticotropic hormone (ACTH) and sheep 0-lipotropic hormone (P-LPH) in solution were studied. It was shown that in trifluoroethanol the greater part of the ACTH molecule assumes an a-helical conformation; however, no final conclusions have been made about the structure of the hormone in aqueous solution.'O2 The far-uv CD study of sheep P-LPH shows that methanol, sodium dodecyl sulfate, and dioxane promote the formation of a-helical structure in the ~eptide.3,~ Intrinsic viscosities and sedimentation coefficients of this hormone suggest that the molecule is not compact and g l~b u l a r .~ Our preliminary spectral studies of the conformation of polypeptide hormones of the pituitary gland in solution and as film^^,^ demonstrate the presence of regular structures that alter with the change in conditions of the medium. The present work has been under-* Present address: Cancer Centre, USSR Academy of Medical Sciences, Moscow, USSR. Biopolymers, Vol. 23,5-22 (1984) taken to study in detail the structural forms of polypeptide hormones (and their fragments) of the anterior lobe of the pituitary gland in solution and as films. Their transformations with changing conditions of the medium and possible functional consequences are also examined. METHODS AND MATERIALSThe CD spectra in the peptide bond absorption region were measured on a Mark I11 Jobin-Yvon dichrograph at 20°C. A cryostat accessory for the Roussel-Jouan CD-185 dichrograph allowed us to alter temperatures in the cell from -195 to 39°C. Heating was accomplished using an ultrathermostat. The sample was kept for not less than 30 min at each temperature. CD was expressed in A6 molar units (l/cm mol pep...

show abstract

“…Moreover, recent circular dichroism studies by St-Pierre et al (21) show that /3-lipotropin is very stable in a wide range of pH and temperature conditions. One can also exclude the possibility that the appearance of f3-endorphin could be due to hydrolytic trypsin-like activity released from broken cells during the incubation for three reasons: (i) the kinetics of protein labeling is linear with time, suggesting little lysis of pituitary cells; (ii) only carefully washed intact pituitary slices have been used for the extraction; (iii) a trypsin inhibitor has been included in the incubation medium.…”

Section: Discussionmentioning

confidence: 98%

In vitro biosynthesis of beta-endorphin in pituitary glands.

Crine¹,

Benjannet²,

Seidah³

et al. 1977

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

#-Endorphin is a 31 amino acid polypeptide isolated from the pituitary gland of different species of animals. It has strong morphine-like activity. It is formed of amino acid residues 61-91 of f-lipotropin. Speculation has arisen whether it is biosynthesized in situ or transformed after secretion of 0-lipotropin. The present in vitro studies show that it is found as fl-endorphin in bovine pituitary slices incubated with radioactive amino acid precursor [asS methionine. Chemical characterization and microsequencing of the newly biosynthesized material proves its identity with isolated unlabeled i-endorphin and shows that it has a methionine residue at its fifth position, as expected. Hughes et al. (1) recently described the isolation of two peptides from hog brains that are agonists of morphine. These peptides were named enkephalins. The first one, Tyr-Gly-Gly-Phe-Met, has a methionine residue in the fifth position and was therefore named Met-enkephalin. It is four times more abundant (in pig brain) than Leu-enkephalin, in which a leucine residue replaces the methionine in the fifth position. The sequence of the five residues of Met-enkephalin is identical to the fragment containing residues 61-65 of f3-lipotropin, a lipolytic hormone produced by the pituitary gland. This discovery prompted several groups to look in pituitary glands for endogenous morphine-like substances structurally related to 3l-lipotropin.Several investigators (2-5) were able to show the presence of such morphine-like substances in human as well as in camel, sheep, and hog pituitaries. All those that have been well characterized have been found to correspond to sequence 61-91 of their respective fl-lipotropin and were named (3-endorphin. The COOH-terminal fragments 61-76 and 61-77 of fl-lipotropin were also extracted from pig hypothalamus-neurohypophysis (6, 7). It was, moreover, observed that while fl-lipotropin had no morphine-like activity, even at high doses (8), the fragment 61-91 had considerable activity in the morphine bioassay and opiate-receptor-binding assays (2,4,8). These findings also clearly indicate that the relaitionship between fl-lipotropins and the opioid peptides is more than accidental.,B-Lipotropin,' whose physiological significance has remained obscure for some time, now appears to be a unique molecule comprising the structures of two biologically active peptides:/-melanotropin (melanocyte-stimulating hormone) (residues 41-58) and Met-enkephalin. The isolation of y-lipotropin by Chretien and Li (9) provided a molecule possessing the structure of an intermediate product between two other known substances, f3-lipotropin and f3-melanotropin. Later, Chretien and Gilardeau (10) showed that fl-lipotropin is very stable and they concluded that 3-lipotropin was likely to be the biological precursor of fl-melanotropin. In 1968, Chance et al. (11) have demonstrated the biosynthesis of both fl-lipotropin and 7y-lipotropin in bovine pituitaries. They were unable to isolate newly synthesized (3-melanotropin because it occ...

show abstract

Circular dichroism studies of sheep β-lipotropic hormone

Cited by 17 publications

References 0 publications

Conformation of beta-endorphin and beta-lipotropin: formation of helical structure in methanol and sodium dodecyl sulfate solutions.

Conformation of beta-endorphin and beta-lipotropin: formation of helical structure in methanol and sodium dodecyl sulfate solutions.

Secondary structure of polypeptide hormones of the anterior lobe of the pituitary gland

In vitro biosynthesis of beta-endorphin in pituitary glands.

Contact Info

Product

Resources

About